This effectively renders those tests useless (since realistically nobody
runs tests locally), but it’s better than every other CI run failing for
unrelated reasons. The idea is that the ‘flaky’ tag can be temporarily
applied to a test while a problem is being investigated or fixed, and
then removed later.
Signed-off-by: Philip Withnall <withnall@endlessm.com>

While we can’t add markers to the macro implementations to cause lcov to
ignore them automatically, we can change our lcov configuration to
ignore all calls to them.
See https://github.com/linux-test-project/lcov/issues/44.
This causes all the un-takeable branches and un-reachable assertions to
be ignored by our code coverage, which bumps our statistics:
• Lines: 74.9% → 74.8%
• Functions: 82.3% → 82.3%
• Branches: 53.3% → 64.2%
The rationale is that nobody should be testing programmer error
handling, as g_return_*if_fail() are used to guard against — so it’s not
reasonable to count missed branches like that in code coverage
statistics.
Signed-off-by: Philip Withnall <withnall@endlessm.com>

The gresource code uses libelf if available but that also depends on mmap but isn't
guarded with HAVE_MMAP. This can make the build fail under MSYS2 where a mingw version
of libelf exists but there is no mmap.
Instead of guarting the libelf code with HAVE_LIBELF add a new macro named USE_LIBELF
which is only defined if libelf and mmap support are available.
Also install the mingw libelf version for CI so we catch similar errors in the future.

See comment in !151. Using the "--initial" option of lcov we collect
the coverage of all compiled files and merge them later into the final
report. This way we can see which files are built but never executed
by the test suite.
Because the --initial switch also collects files in the ccache directory
we have to point it to the build directory instead, which in turn breaks
--no-external. Instead of using --no-external in the collection step,
filter out any files not in the source tree in the final coverage job
through a path filter.

- Split the download part into a separate script to so docker keeps that
step in cache and avoid redownloading it.
- With API level >= 28 libiconv is not needed anymore because it's part
of Android's libc.
- Generate standalone toolchains to reduce the docker image size. It's
also easier because it doesn't need to pass sysroot args.
- Use clang compiler because gcc is deprecated in this Android NDK and
will be removed in the next release.

We should be testing latest NDK release but keep using API level 21 to
ensure GLib does not start using newer APIs. We could also later add a
runner for latest API level 28 which includes iconv API in Android's
libc so we don't need GNU libiconv anymore.

This adds to the CI a cross build for Android NDK r16 API 21 (because
thats what GStreamer currently use) for arm64.
GNU iconv must be built manually into our docker image because Android
NDK doesn't seems to ship it. The latest NDK r17 API 28 has iconv.h but
iconv_open() symbol isn't found by the linker. Looks like broken NDK.
libffi also needs to be built manually because the meson subproject
doesn't support building for Android platform. It needs a recent RC
release because latest stable release is 4 years old and fails to
build.
Fixes #1385.

Use lcov for both Fedora and MSYS2 to create coverage reports and add a second
ci stage which merges the coverage and creates a html report using genhtml.
In the final stage, which is only run on master, the result is published on
gitlab pages.
https://bugzilla.gnome.org/show_bug.cgi?id=795636

Fix various warnings regarding unused variables, duplicated
branches etc by adjusting the ifdeffery and some missing casts.
gnulib triggers -Wduplicated-branches in one of the copied files,
disable as that just makes updating the code harder.
The warning indicating missing features are made none fatal through
pragmas. They still show but don't abort the build.
https://bugzilla.gnome.org/show_bug.cgi?id=793729

This builds glib using meson/ninja/ccache with mingw-w64 on a Windows
machine.
The CI scripts expect a gitlab runner to exist with the "win32" tag
which uses the default "cmd" shell by default.
Before running the tests pacman is invoked to update the system
(potentially including bash etc, thus the extra step)
Then a login shell is started with CHERE_INVOKING to not change the
cwd and finally the test script is executed.
https://bugzilla.gnome.org/show_bug.cgi?id=793729

We're mostly interested into building and testing everything that gets
pushed to the repository — including merge requests.
When pushing tags, though, we should assume we're spinning a release, so
let's run the dist target, and store the tarball, and the generated
documentation while we're at it, as artifacts on GitLab.
The Dockerfile for the image used for the build is included in tree, and
published on Docker Hub. Using a custom image allows us to avoid the
costly "download and install build dependencies" phase, as well as
controlling the environment a little bit better.
https://bugzilla.gnome.org/show_bug.cgi?id=793635